Nt1310 Unit 6 Lab Report
2012
Table of Contents
Page #
1.0 Design
1.1 Focus Question 2
1.2 Hypothesis 2
1.3 Background Theory 2
1.4 Variables in the Investigation 4
1.5 Controlled Variables 5
1.6 Apparatus & Chemicals 5
1.7 Risk Assessment 6
1.8 Experimental Method 8
1.9 Lab Setup 9
1.0 Design
1.1 Focus Question
What is the relationship between increasing atomic number of elements along period three and melting point (oC) measured using a heating block?
1.2 Hypothesis
When atomic number along period three is plotted against the melting point, the melting point will increase until it reaches silicon then melting …show more content…
point will decrease.
1.3 Background Theory
Melting point is the point at which the solid phase will convert to a liquid phase. Melting points vary, depending on the strength of forces which exist between the particles that make up a substance and can be used to characterize and determine a particular substance. Melting point can be measured using a Fisher-Johns melting point apparatus which uses a sample on a lens which is placed on the apparatus and heated. The operator is able to observe the phase change through a magnifying glass.
Figure One: Fisher-Johns Melting Point Apparatus
By determining the melting point of a compound it is possible to tell if the substance is pure. Generally, pure substances have a melting range (the difference between the temperature where the sample starts to melt and the temperature where melting is complete) of one or two degrees. Impurities tend to depress and broaden the melting range so the purified sample should have a higher and smaller melting range than the original, impure sample.
Physical properties such as melting point depend on the bonding between the particles of the element. From previous experiments it has been determined that at the left of the period the elements are metallic and going across the period the strength of the metallic bonding increases as there is an increase in nuclear charge, giving rise to an increase in the melting points as the metal cations are held closer and more tightly. At the center of the period silicon forms a giant covalently bonded structure where every atom is joined to all the others by very strong covalent bonds thus giving it a very high melting point. Following this, the melting points suddenly drop due to the weak van der Waals’ forces that exist between molecules . This is shown in figure two.
Figure Two: Melting Points of Elements in Period Three
It can be deduced from the graph and information above that the trend across period 3 for melting point will be that as atomic number increases from left to right melting point will increase from Na to Si with a large increase in melting point from Al to Si. Melting point will then decrease from Si to Cl with a large decrease from Si to P.
However, it is known that only the first six elements are solid at room temperature. Chlorine, unlike the others is not and therefore its melting point cannot be measured using the Fisher- Johns melting point apparatus as samples must be solids. Therefore for the purposes of this investigation it will be excluded and its melting point will not be calculated as it is not easily measureable. Sodium is a highly reactive alkali metal. To prevent contact with air and water it must be kept under kerosene.
1.4 Variables in the Investigation
Variable Identified
Type of Variable
Method of Control/Measurement
Substance Analyzed
(Na, Mg, Al, Si, P and S)
Independent
The substances will be measured in the solid phase. Cl will be excluded as it is not in the solid phase at room temperature. Melting Point
Dependent
This will be measured in oC and identified through observation of the substance through a magnifying glass on the Fisher-Johns melting point apparatus. The temperature at which the substance is observed to start melting and at which it is observed to be completely melted (melting range) will be recorded.
Amount of substance analyzed
Type of melting point apparatus used
Melting point capillaries used
Temperature of the laboratory
Purity of the substance
Concentration of substance
State of substance being melted
Number of repeat trials
Controlled
See ‘Table Two: Controlled Variables and Methods of Control’.
Error in identification of melting point.
Uncontrolled
Subjective interpretation of changes observed in the sample (visually or automatically) during the analysis can lead to unreliable results
1.5 Controlled Variables
Table Two: Controlled Variables and Methods of Control
Controlled Variable
Method of Control
Amount of substance analysed
Each capillary will be filled with 3mm of the powdered compound being tested
Type of melting point apparatus used
The same Fisher-John melting point apparatus will be used for each sample tested
Melting point capillaries used
The same type of melting point capillary will be used for each sample however a new capillary will be used for each sample.
Temperature of the laboratory
The laboratory will remain at a constant room temperature of 21oC throughout the investigation
Purity of the substance
All substances used during the investigations will be pure substances
Concentration of substance
All substances will be of 1M concentration.
State of substance being melted
The substance being melted will be in the solid phase but will be crushed into a fine powder using a motar and pestle in order to allow for an equal rate of reaction.
Number of repeat trials
For each substance being tested (Na, Mg, Al, Si, P, S), three repeat trials will be performed.
1.6 Apparatus & Chemicals
Apparatus/Chemical Name
Scale/Uncertainty/Other Specifications
Quantity
Fisher-Johns Melting Point Apparatus
--
1
Fisher- Johns Melting Point Apparatus Lens Covers
--
36
Spatula
--
1
Sodium
Powdered form
5g
Magnesium
Powdered form
5g
Aluminum
Powder form
5g
Silicon
Powdered form
5g
Phosphorus
Powdered form
5g
Sulfur
Powdered form
5g
1.7 Risk Assessment
Safety Concern
Risk
Precaution
MSDS Reference
1M Sodium (Powdered)
Reacts violently with water liberating extremely flammable gases. Causes burns. Risk of serious damage to eyes. Cumulative effects may result following exposure
Never add water to this product. Keep locked up. Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear suitable protective clothing. Wear suitable gloves. Wear eye/ face protection. Keep container dry. Take off immediately all contaminated clothing.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre.
In case of accident or if you feel unwell, IMMEDIATELY contact Doctor or Poisons Information Centre (show label if possible).
This material and its container must be disposed of as hazardous waste.
Hazardous Substance
1 M Magnesium (powdered) Highly flammable. Contact with water liberates extremely flammable gases. Spontaneously flammable in air. Inhalation may produce health damage*. Avoid contact with eyes.
Cumulative effects may result following exposure*.May produce discomfort of the eyes*.
Never add water to this product. Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear eye/ face protection. Use only in well ventilated areas.
Keep container in a well ventilated place.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre.
This material and its container must be disposed of as hazardous waste.
Non-Hazardous Substance
1M Aluminum
(powdered)
Contact with water liberates extremely flammable gases.
Spontaneously flammable in air. Inhalation may produce health damage Never add water to this product. Do not breathe dust. Avoid contact with skin. Use only in well ventilated areas. Keep container in a well ventilated place.
Non-Hazardous Substance
1M Silicon
(powdered)
Irritating to eyes, respiratory system and skin. Inhalation may produce health damage. Cumulative effects may result following exposure.
Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear suitable gloves. Wear eye/ face protection. Use only in well ventilated areas.
Keep container in a well ventilated place. To clean the floor and all objects contaminated by this material, use water and detergent.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre. If swallowed, IMMEDIATELY contact Doctor or Poisons Information Centre (show this container or label).
Hazardous Substance
1M Phosphorus
(powdered)
Inhalation may produce health damage. Cumulative effects may result following exposure.
Do not breathe dust. Avoid contact with skin. Use only in well ventilated areas. Keep container in a well ventilated
place.
Non-Hazardous Substance
1M Sulfur (powdered)
Cumulative effects may result following exposure. Possible skin sensitizer. Avoid contact with skin. Possible cancer-causing agent.
Do not breathe dust. Avoid contact with skin. Avoid exposure - obtain special instructions before use. This material and its container must be disposed of as hazardous waste.
Non-Hazardous Substance
1.8 Experimental Method
In this investigation, the trends in melting point across period three will be observed.
1. Place a lens cover in the circular well
2. Use the spatula to scoop a small amount of powdered substance and place it onto the lens cover. (See Figure Two)
3. Place another lens cover on top of the substance and move the magnifying glass over the well. (See Figure One)
4. Turn on the machine and slowly elevate the temperature using the dial.
5. Watch the substance through the magnifying glass and record the temperature at which it can be observed to be starting to melt.
6. Continue to slowly elevate the temperature until the substance has completely melted, record that temperature.
7. Remove and dispose of both lens covers and repeat this process three times for each substance being measured.
1.10 Lab Setup
Figure One: Fisher-Johns Melting Point Apparatus
Figure Two: Substance on lens cover
Figure Three: Substance after being melted
Bibliography
Bentor, Y. (2009). Periodic Table: Alkali Metals . Retrieved May 7, 2012, from Chemicalelements.com: http://www.chemicalelements.com/groups/alkali.html
Brown, C. (2009). Higher Level Chemistry . Wales : Pearson Education Limited .
Green, J. (2007). Chemistry . Victoria : IBID Press.
Saunders, N. (2008, December 29). Trends in melting and boiling points in Period 3. Retrieved May 9 , 2012, from Creative Chemistry : http://www.creative-chemistry.org.uk/alevel/module1/trends8.htm
Thelguana. (2008, October 14). Fisher-Johns Melting Point Apparatus. Retrieved May 7, 2012 , from flickr.com: http://www.flickr.com/photos/51035797337@N01/2943119729
Yoder, C. (2012 ). Determination of Melting Point . Retrieved May 7, 2012 , from Wired Chemist : http://www.wiredchemist.com/chemistry/instructional/laboratory-tutorials/determination-of-melting-point
Table of Contents
Page #
1.0 Design
1.1 Focus Question 2
1.2 Hypothesis 2
1.3 Background Theory 2
1.4 Variables in the Investigation 4
1.5 Controlled Variables 5
1.6 Apparatus & Chemicals 5
1.7 Risk Assessment 6
1.8 Experimental Method 8
1.9 Lab Setup 9
1.0 Design
1.1 Focus Question
What is the relationship between increasing atomic number of elements along period three and melting point (oC) measured using a heating block?
1.2 Hypothesis
When atomic number along period three is plotted against the melting point, the melting point will increase until it reaches silicon then melting …show more content…
point will decrease.
1.3 Background Theory
Melting point is the point at which the solid phase will convert to a liquid phase. Melting points vary, depending on the strength of forces which exist between the particles that make up a substance and can be used to characterize and determine a particular substance. Melting point can be measured using a Fisher-Johns melting point apparatus which uses a sample on a lens which is placed on the apparatus and heated. The operator is able to observe the phase change through a magnifying glass.
Figure One: Fisher-Johns Melting Point Apparatus
By determining the melting point of a compound it is possible to tell if the substance is pure. Generally, pure substances have a melting range (the difference between the temperature where the sample starts to melt and the temperature where melting is complete) of one or two degrees. Impurities tend to depress and broaden the melting range so the purified sample should have a higher and smaller melting range than the original, impure sample.
Physical properties such as melting point depend on the bonding between the particles of the element. From previous experiments it has been determined that at the left of the period the elements are metallic and going across the period the strength of the metallic bonding increases as there is an increase in nuclear charge, giving rise to an increase in the melting points as the metal cations are held closer and more tightly. At the center of the period silicon forms a giant covalently bonded structure where every atom is joined to all the others by very strong covalent bonds thus giving it a very high melting point. Following this, the melting points suddenly drop due to the weak van der Waals’ forces that exist between molecules . This is shown in figure two.
Figure Two: Melting Points of Elements in Period Three
It can be deduced from the graph and information above that the trend across period 3 for melting point will be that as atomic number increases from left to right melting point will increase from Na to Si with a large increase in melting point from Al to Si. Melting point will then decrease from Si to Cl with a large decrease from Si to P.
However, it is known that only the first six elements are solid at room temperature. Chlorine, unlike the others is not and therefore its melting point cannot be measured using the Fisher- Johns melting point apparatus as samples must be solids. Therefore for the purposes of this investigation it will be excluded and its melting point will not be calculated as it is not easily measureable. Sodium is a highly reactive alkali metal. To prevent contact with air and water it must be kept under kerosene.
1.4 Variables in the Investigation
Variable Identified
Type of Variable
Method of Control/Measurement
Substance Analyzed
(Na, Mg, Al, Si, P and S)
Independent
The substances will be measured in the solid phase. Cl will be excluded as it is not in the solid phase at room temperature. Melting Point
Dependent
This will be measured in oC and identified through observation of the substance through a magnifying glass on the Fisher-Johns melting point apparatus. The temperature at which the substance is observed to start melting and at which it is observed to be completely melted (melting range) will be recorded.
Amount of substance analyzed
Type of melting point apparatus used
Melting point capillaries used
Temperature of the laboratory
Purity of the substance
Concentration of substance
State of substance being melted
Number of repeat trials
Controlled
See ‘Table Two: Controlled Variables and Methods of Control’.
Error in identification of melting point.
Uncontrolled
Subjective interpretation of changes observed in the sample (visually or automatically) during the analysis can lead to unreliable results
1.5 Controlled Variables
Table Two: Controlled Variables and Methods of Control
Controlled Variable
Method of Control
Amount of substance analysed
Each capillary will be filled with 3mm of the powdered compound being tested
Type of melting point apparatus used
The same Fisher-John melting point apparatus will be used for each sample tested
Melting point capillaries used
The same type of melting point capillary will be used for each sample however a new capillary will be used for each sample.
Temperature of the laboratory
The laboratory will remain at a constant room temperature of 21oC throughout the investigation
Purity of the substance
All substances used during the investigations will be pure substances
Concentration of substance
All substances will be of 1M concentration.
State of substance being melted
The substance being melted will be in the solid phase but will be crushed into a fine powder using a motar and pestle in order to allow for an equal rate of reaction.
Number of repeat trials
For each substance being tested (Na, Mg, Al, Si, P, S), three repeat trials will be performed.
1.6 Apparatus & Chemicals
Apparatus/Chemical Name
Scale/Uncertainty/Other Specifications
Quantity
Fisher-Johns Melting Point Apparatus
--
1
Fisher- Johns Melting Point Apparatus Lens Covers
--
36
Spatula
--
1
Sodium
Powdered form
5g
Magnesium
Powdered form
5g
Aluminum
Powder form
5g
Silicon
Powdered form
5g
Phosphorus
Powdered form
5g
Sulfur
Powdered form
5g
1.7 Risk Assessment
Safety Concern
Risk
Precaution
MSDS Reference
1M Sodium (Powdered)
Reacts violently with water liberating extremely flammable gases. Causes burns. Risk of serious damage to eyes. Cumulative effects may result following exposure
Never add water to this product. Keep locked up. Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear suitable protective clothing. Wear suitable gloves. Wear eye/ face protection. Keep container dry. Take off immediately all contaminated clothing.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre.
In case of accident or if you feel unwell, IMMEDIATELY contact Doctor or Poisons Information Centre (show label if possible).
This material and its container must be disposed of as hazardous waste.
Hazardous Substance
1 M Magnesium (powdered) Highly flammable. Contact with water liberates extremely flammable gases. Spontaneously flammable in air. Inhalation may produce health damage*. Avoid contact with eyes.
Cumulative effects may result following exposure*.May produce discomfort of the eyes*.
Never add water to this product. Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear eye/ face protection. Use only in well ventilated areas.
Keep container in a well ventilated place.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre.
This material and its container must be disposed of as hazardous waste.
Non-Hazardous Substance
1M Aluminum
(powdered)
Contact with water liberates extremely flammable gases.
Spontaneously flammable in air. Inhalation may produce health damage Never add water to this product. Do not breathe dust. Avoid contact with skin. Use only in well ventilated areas. Keep container in a well ventilated place.
Non-Hazardous Substance
1M Silicon
(powdered)
Irritating to eyes, respiratory system and skin. Inhalation may produce health damage. Cumulative effects may result following exposure.
Do not breathe dust. Avoid contact with skin. Avoid contact with eyes. Wear suitable gloves. Wear eye/ face protection. Use only in well ventilated areas.
Keep container in a well ventilated place. To clean the floor and all objects contaminated by this material, use water and detergent.
In case of contact with eyes, rinse with plenty of water and contact Doctor or Poisons Information Centre. If swallowed, IMMEDIATELY contact Doctor or Poisons Information Centre (show this container or label).
Hazardous Substance
1M Phosphorus
(powdered)
Inhalation may produce health damage. Cumulative effects may result following exposure.
Do not breathe dust. Avoid contact with skin. Use only in well ventilated areas. Keep container in a well ventilated
place.
Non-Hazardous Substance
1M Sulfur (powdered)
Cumulative effects may result following exposure. Possible skin sensitizer. Avoid contact with skin. Possible cancer-causing agent.
Do not breathe dust. Avoid contact with skin. Avoid exposure - obtain special instructions before use. This material and its container must be disposed of as hazardous waste.
Non-Hazardous Substance
1.8 Experimental Method
In this investigation, the trends in melting point across period three will be observed.
1. Place a lens cover in the circular well
2. Use the spatula to scoop a small amount of powdered substance and place it onto the lens cover. (See Figure Two)
3. Place another lens cover on top of the substance and move the magnifying glass over the well. (See Figure One)
4. Turn on the machine and slowly elevate the temperature using the dial.
5. Watch the substance through the magnifying glass and record the temperature at which it can be observed to be starting to melt.
6. Continue to slowly elevate the temperature until the substance has completely melted, record that temperature.
7. Remove and dispose of both lens covers and repeat this process three times for each substance being measured.
1.10 Lab Setup
Figure One: Fisher-Johns Melting Point Apparatus
Figure Two: Substance on lens cover
Figure Three: Substance after being melted
Bibliography
Bentor, Y. (2009). Periodic Table: Alkali Metals . Retrieved May 7, 2012, from Chemicalelements.com: http://www.chemicalelements.com/groups/alkali.html
Brown, C. (2009). Higher Level Chemistry . Wales : Pearson Education Limited .
Green, J. (2007). Chemistry . Victoria : IBID Press.
Saunders, N. (2008, December 29). Trends in melting and boiling points in Period 3. Retrieved May 9 , 2012, from Creative Chemistry : http://www.creative-chemistry.org.uk/alevel/module1/trends8.htm
Thelguana. (2008, October 14). Fisher-Johns Melting Point Apparatus. Retrieved May 7, 2012 , from flickr.com: http://www.flickr.com/photos/51035797337@N01/2943119729
Yoder, C. (2012 ). Determination of Melting Point . Retrieved May 7, 2012 , from Wired Chemist : http://www.wiredchemist.com/chemistry/instructional/laboratory-tutorials/determination-of-melting-point